ISSN:1056-6163    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

Placing a dental implant elicits a time-dependent bone response controlled by wound-healing factors (cytokines, bioetectrical signals), biomechanics (gravitational, functional, and therapeutic loads), and mineral metabolism (hormones, diet, excretion). The osseous response to an implant involves four physiological stages: (1) endosteal and periosteal callus formation; (2) compaction and remodeling of the callus; (3) remodeling (turnover) of the nonvital interface and adjacent bone; and (4) maturation (secondary mineralization) of new bone. Long-term maintenance of a rigid implant interface is related to continual bone remodeling. Common metabolic bone disorders affecting potential implant patients are osteopenia (“osteoporosis”), renal osteodystrophy, osteomalacia, and Paget's disease. The most prevalent problem is a long-term negative calcium balance leading to a compromise in bone strength. Symptomatic osteoporosis (usually wrist, hip, and/or spine fractures) affects 4 to 50 percent of the population depending on age, race, sex, endocrine status, and life-style. Postmenopausal white and Asian females present the greatest risk. The jaws of “osteoporotic” adults are variably affected because of the moderating influence of mechanical function. Management of metabolic bone disorders is an important consideration in diagnosis, treatment planning, and long-term monitoring of dental implants. Bone metabolic counseling, a natural extension of preventative dentistry, is an unexpected benefit readily appreciated by patients and their families. (Implant Dent 1992;1:11–21)

ISSN:1056-6163    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

This article describes treatment of the ailing implant (bone loss with pocketing but static at the maintenance checks) and the failing implant (bone loss with pocketing, bleeding upon probing, purulence, and evidence of continuing bone loss irrespective of therapy): Because the surface of the implant is contaminated with endotoxin, it must be detoxified before any regenerative therapy. Studies have shown that citric acid is effective in detoxifying the hydroxyapatite-coated surfaces while tetracycline is more effective in sterilizing the metallic substrate fixtures. Guided tissue regeneration is useful as a “barrier” to prevent exfoliation of the grafted material. Both nonresorbable and resorbable materials have been used with great success. Allografts (freeze-dried bone) and attoplasts (synthetic materials) may be used to achieve a sulcus of decreased depth and possibly some type of osseous regeneration. The author recommends the use of the allograft if the surface is completely detoxified and the alloplast if it is not certain that the surface is sterilized and free of endotoxin. The allograft, being resorbable, will not effect biologic healing against a contaminated surface; hence, the use of the alloplast to fill the defect and prevent epithelial invagination. (Implant Dent 1992;1:25–33)

ISSN:1056-6163    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

A blade implant that was retrieved in 1990 after 231 months of clinical function (since 1971) was analyzed with respect to clinical, histological, and biomechanical characteristics. The implant clinical records demonstrated no abnormalities or pathological lesions over the tenure of treatment. The bone to implant interface showed a mixture of interfacial tissue components and conditions with adequate direct bone contact (46.4 to 82.3 percent) for classification as osseointegrated. The abutment fracture leading to removal was characterized as a cyclic fatigue mechanism and the distribution of tissue components along the interface could not be correlated with specific biomechanical loading directions. This report considers the clinical and biomechanical records as they relate to the detailed histological investigation. (Implant Dent 1992;1:37–43)

ISSN:1056-6163    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

This investigation is designed to provide scientific data that is directly relevant to the placement of dental implants. The study is concerned with the influence of implant design, application, and location on long-term clinical performance and crestal bone response over 5 years of function. It involves approximately 700 patients at 30 Veterans Administration Medical Centers from various geographic regions. Patients are being entered into the study over an 18-month period and monitored (post-loading) over 5 years. The participating centers were randomly assigned to one of two separate, independent study groups. Complications and adverse responses associated with the placement and use of the implants will be evaluated and all failures thoroughly documented. The experimental design and sample size are based on the primary hypothesis that an implant-supported prosthesis will be successful/functional over a 5-year period in at least 90 percent of the cases treated. Secondary hypotheses to be tested are (1) the success rate among implant designs are the same over a 5-year period; (2) the success rate among implant applications are the same over a 5-year period; (3) the success rate of individual implants are the same with regard to jaw location over a 5-year period; (4) the loss of crestal bone at the individual implant sites are the same among the implant designs over a 5-year period; and (5) the complications and adverse responses experienced with the different implant designs are the same over a 5-year period. The experimental design of this multicenter, multidisciplinary, randomized investigation is a cooperative effort of the Department of Veterans Affairs and several United States dental schools. (Implant Dent 1992;1:49–55)

ISSN:1056-6163    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

Overdenture techniques can be modified for use with implants. Generally the implants, which replace the tooth roots, can be placed in a position to permit optimum retention and stability as well as enhancing esthetics. Bony undercuts, which at times are present with the retention of tooth roots, are not a problem when using implants. Various retentive schemes are available to retain the prosthesis and can be matched to the individual needs of patients in regard to retention, stability, and the ability to insert and remove prostheses. Two implants can adequately support an overdenture. The superstructure must be designed to enable the patient to maintain a healthy oral environment. The patient must understand and be able to perform required oral hygiene procedures. The use of overdentures over implants affords the dentist another option in meeting the needs of the patients. (Implant Dent 1992;1:69–77)

ISSN:1056-6163    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

The accuracy of determining marginal bone height changes around osseointegrated implants depends on the validity of comparing serial films and the reliability of the measurements. X-ray beam orientation changes can alter the validity of serial films. A human dry mandible containing a Brånemark implant was irradiated ±12 degrees in the vertical plane at 1-degree intervals to the perpendicular to the long axis of the fixture. The thread width was recorded on both sides of each fixture image using a computer. Twenty-five randomized unclassified images were remeasured and the vertical angle of the x-ray beam was estimated from the previous measurements to test for validity of comparing images. The reliability of measurements with altered image magnification and penumbra were calculated. The reliability of 24 repeated thread width measurements was a SD of 0.01 mm. Of the 25 unknown beam angulations, 32 percent matched correctly, 20 percent ± 1 degree, 16 percent ± 2 degrees, or 68 percent <m ±2 degrees. Alteration from a short to a long cone technique was estimated to produce magnification errors similar to the reliability SD of 0.01 mm. Similarly the penumbra varied from 0.057 mm to 0.032 mm with short to long cones using a 1.0-mm focal spot. With a 0.6-mm focal spot, the smallest penumbra of 0.19 mm was twice the measurement reliability. This method demonstrated x-ray beam angulation and validity for comparing serial films can be estimated for the extreme variations but not accurately for +9 to −6 degrees from a tangent to the fixture. Small focal spot, long cone techniques are needed to match the reliability of the method. Achieving valid bone loss measurements < 0.2 mm is extremely difficult. (Implant Dent 1992;1:79–83)

ISSN:1056-6163    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

This pilot project attempted to demonstrate microscopic evidence of osseointegration in a controlled environment as originally presented by Brånemark. The Interfacial Biopsy Chamber was developed to collect titanium/tissue serial biopsies of the implant-tissue interface at various stages of wound healing. It was surgically placed in two Flemish giant rabbits and titanium/tissue biopsies were collected at 35 and 70 days. The biopsies were examined using scanning electron microscopy (x2000, x3200, and x7500) and light microscopy (x230). Osseous tissue was found in intimate contact with the titanium implant surface with no evidence of an intervening fibrous layer. Cells with the morphological characteristics of osteoblasts were observed covering the titanium surface. Processes extending from the main body of these cells were in intimate contact with the titanium surface, following the machining striations. The photomicrographs were similar to those presented earlier by Brånemark. The project also suggested the use of the Interfacial Biopsy Chamber as a research instrument for the collection of implant/tissue interface serial biopsy samples. (Implant Dent 1992;1:84–87)

ISSN:1056-6163    

出版商:OVID    

年代:1992

数据来源: OVID

ISSN:1056-6163    

出版商:OVID    

年代:1992

数据来源: OVID

ISSN:1056-6163    

出版商:OVID    

年代:1992

数据来源: OVID